Pathology of Brain Metastasis

Brain metastasis is the most life-threatening complication of cancer dissemination. The biological hurdles tumor cells have to overcome to reach the brain include the blood-brain barrier, but also the barriers between cerebrospinal fluid and ependymal or choroid plexus. There are differences between tumors in their predilection to seed to brain that may relate to intrinsic cellular properties, but also switching on various molecular pathways. We are only beginning to unravel some of the molecular cascades cells utilize to penetrate the barriers and successfully grow into brain. Combatting cerebral metastases therefore should involve drugs targeted to the molecules operative in the various successive stages of the process of brain invasion.